1. Field of the Invention
The present invention relates to a frame assembly of a ring-type fan, and in particular to a frame assembly of a ring-type fan with a pressure-releasing function, which is capable of delaying the deceleration, improving the fan performance, and reducing its noise.
2. Description of Prior Art
Nowadays, electronic products are gradually developed to have a high performance, a high frequency, a high speed, and a compact size. As a result, the amount of heat generated in the electronic product is increased to a greater extent, so that the operating state of such an electronic product becomes unstable and is always at a higher temperature, which affects the reliability and lifetime of the electronic product. Thus, it is an important issue for the manufacturers in this field to improve the heat dissipation for the electronic product. A fan is a common device used for this purpose.
Vortexes are often generated among blades of the fan during its operation. The vortexes affects the performance (such as the total air amount) of the fan. Thus, a ring-type fan is developed to solve this problem.
Please refer to FIGS. 1A and 1B showing a conventional ring-type fan. The conventional ring-type fan 1 includes a frame body 10 and a fan wheel 11. The frame 10 has an air-exiting side 101, an air-entering side 102 and a shaft portion 104. An accommodating space 12 is defined between the air-exiting side 101 and the air-entering side 102. The fan wheel 11 is disposed in the accommodating space 12. The shaft portion 104 is disposed in the center of the accommodating space 12 and pivotally connected to the fan wheel 11.
The fan wheel 11 has a hub 111 and a plurality of blades 112 circumferentially provided on the outer periphery of the hub 111. An annular body 14 is formed by connecting the free ends of the blades. A gap 15 is formed between the annular body 14 and the inner wall of the frame body 10. By this arrangement, when the fan is in operation, the annular body 14 can reduce the generation of vortexes among the blades 112, thereby improving the fan performance.
Although the conventional ring-type fan 1 can reduce the generation of vortexes by means of the annular body 14, another problem rises. Since the airflow enters the air-entering side 102 and exits the air-exiting side 101 when the ring-type fan 1 is operating, a negative pressure is generated on the air-exiting side 101. As a result, a portion of airflow exiting the air-exiting side 101 flows back and exits the annular body 14 via the gap 15. This portion of airflow exiting the annular boy 14 via the gap 15 will interference with the airflow entering the annular body 14, which causes turbulent flows on the air-entering side 102. As a result, the air entering the air-entering side 102 cannot flow smoothly, which reduces the fan performance and increases the noise.
According to the above, the conventional ring-type fan has the following drawbacks:
(I) reduced in the fan performance; and
(II) increased in its noise.
In order to solve the above-mentioned problems, the present inventor proposes a novel and reasonable structure based on his expert knowledge and deliberate researches.